Influence of composition and microstructure on transparency and diffusivity in ion‐exchangeable spinel glass‐ceramics
Alexandra L. Mitchell, Charlene M. Smith
Abstract
Abstract Ion‐exchangeable, transparent spinel glass‐ceramics are presented and discussed here for the first time. To retain transparency with increasing crystallinity, spinel glass‐ceramics must have uniform crystallization of small (~9 nm) crystallites, not large spherulitic structures comprised of small crystallites. To obtain such a uniform microstructure, the amount of total nucleating agents (ZrO 2 + TiO 2 ) in the precursor glass composition must be greater than 5 mol%. With small changes in composition and significant differences in microstructure, the demarcation between transparent and opaque glass‐ceramics is distinct as is the decrease in K diffusivity during ion‐exchange from the transparent (14.7 microns 2 /h) to the opaque (11.2 microns 2 /h) compositions. Understanding how to retain transparency during ceramming and increase diffusivity during chemical strengthening is critical in designing materials for many real‐world applications. Ion‐exchangeable, transparent spinel glass‐ceramics are presented and discussed here for the first time. To retain transparency with increasing crystallinity, spinel glass‐ceramics must have uniform crystallization of small (~9 nm) crystallites, not large spherulitic structures comprised of small crystallites. To obtain such a uniform microstructure, the amount of total nucleating agents (ZrO 2 + TiO 2 ) in the precursor glass composition must be greater than 5 mol%. With small changes in composition and significant differences in microstructure, the demarcation between transparent and opaque glass‐ceramics is distinct as is the decrease in K diffusivity during ion‐exchange from the transparent (14.7 microns 2 /h) to the opaque (11.2 microns 2 /h) compositions. Understanding how to retain transparency during ceramming and increase diffusivity during chemical strengthening is critical in designing materials for many real‐world applications.